Experimental results in rodents have suggested that exposure to cholesterol during suckling may have a long-term or imprinting effect on cholesterol synthesis later in life. No studies have addressed whether there is an "imprinting" effect on cholesterol synthesis that is affected by exposure to cholesterol during suckling. This study is designed to test the hypothesis that varying exposure to cholesterol during the suckling period in infants will lead to lasting effects of "imprinting" on cholesterol synthesis.